English: Fire corals; Hydroids; Hydroid jellyfishes; Siphonophores.
Name: from Greek hydōr meaning water" and zōion meaning animal.
Clades:
Cnidaria;
Radiata;
Animals.
Genera: 3600 species.
ZoologyHydrozoa are very small, predatory animals, some are solitary and some colonial, most living in salt water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony.
A few genera within this class live in fresh water: freshwater jelly Craspedacusta sowerbyi, freshwater polyps Hydra, Obelia, Portuguese man o' war
Physalia physalis, chondrophores Porpitidae, Air fern Sertularia argentea, and pink-hearted hydroids Tubularia.
FamiliesHydroidolina
• Anthoathecata
• Aplanulata
• Capitata
• Filifera
• Leptothecata
• Siphonophorae
Trachylinae
• Actinulida
• Limnomedusae
• Narcomedusae
• Tatalidoae